The regulation of the volume and composition of the body fluids is primarily dependent upon vasopressin (ADH, antidiuretic hormone), the renin-angiotensin-aldosterone system, and possibly a humoral natriuretic factor. Futhermore, the control of blood volume has been recognized to be an important factor in the regulation of arterial blood pressure. The primary objective of this research proposal, as well as the applicant's long-term research goal, is to delineate the role of ADH in these regulatory processes. In the past, our emphasis was largely upon the study of receptors located in the cardiovascular system, which play a role in the volume control of ADH release. The present application will be concerned with two different lines of investigation. In one, we shall continue to characterize the removal of ADH from the circulation and to determine the extent to which this removal is under physiological control. In the other, we shall continue to study the possible role in the release and metabolism of ADH of other humoral factors which are involved in water and electrolyte metabolism.